Levi and Yehudah both claimed that a certain field was of their fathers. Levi brought witnesses that it was his father's, and Yehudah brought witnesses that he used the field for the years of Chazakah.

Rabah: Certainly, Yehudah is telling the truth. Why should he lie and say that it belonged to his father? If he wanted to lie, he could make a better claim, that he bought it from Levi, and used it for the years of Chazakah!

Objection (Abaye): The principle 'why should he lie' does not override witnesses (who say that it belonged to Levi's fathers)!

Yehudah later retracted: Yes, it belonged to your fathers. I bought it from you. I said that it was my fathers', for (since I made a Chazakah,) I am confident of keeping it like one who inherited his fathers' land

Question: Can one claim, and then change his claim?

Answer #1 (Ula): One can/

Answer #2 (Chachamim of Neharde'a): One cannot.

In two cases, Ula admits that he cannot change his claim;

He initially said 'it belonged to my fathers, and not to your fathers.'

He did not make a claim in Beis Din, and after he left Beis Din, he returns and claims.

Question: Why is this not allowed?

Answer: We suspect that others instructed him how he should claim.

In two cases, Chachamim of Neharde'a admit that he can change his claim.

He later says 'it belonged to my fathers, who bought it from your fathers.'

They were discussing the case outside of Beis Din, and he did not make any claim, and when he came to Beis Din, he made a claim.

Question: Why is this allowed?

Answer: It is normal that one reveals his claims only in Beis Din.

(Ameimar): I am from Neharde'a, yet I hold that one may change his claim.

The Halachah is, one may change his claim.

Levi and Yehudah both claimed that they inherited a field from their fathers. Levi brought witnesses that it was his father's and that he has used the field for the years of Chazakah, and Yehudah brought witnesses that he used the field for the years of Chazakah.

(Rav Nachman): The contradictory testimonies about the Chazakah cancel each other. We are left with testimony that it belonged to Levi's fathers.

Question (Rava): The testimonies contradict each other. We cannot rely on either testimony!

Answer (Rav Nachman): The contradiction is only regarding Chazakah, but not regarding to whose fathers it belonged.

Suggestion: Rava and Rav Nachman argue as Rav Huna and Rav Chisda.

(Rav Huna): If two sets of witnesses contradict each other, either set may testify by itself in a different case.

(Rav Chisda): Since we are in doubt which set lied, we do not accept the testimony of either set.

Rejection: Indeed, Rav Chisda must hold like Rava;

However, Rav Huna could hold like Rav Nachman, or even like Rava.

Rav Huna said that we accept the testimony of one set of witnesses in subsequent cases. He could admit that we do not accept their testimony in the case in which they were contradicted!

After Rav Nachman ruled that the field belongs to Levi, Yehudah brought witnesses that it was his father's.

Rav Nachman: We established Levi to be the owner of the field. We remove him from it (and whoever is stronger will prevail). We are not concerned for the disgrace to Beis Din (that we contradict our previous ruling).

Question (Rava - Beraisa): If two witnesses say that Leah's husband died, and two say that he did not die; or two witnesses say that she was divorced, and two say that she was not divorced, she may not remarry. If she remarried, we do not force her husband to divorce her;

R. Menachem b'Rebbi Yosi says, he must divorce her. This is only if she remarried after the witnesses who said that she is still married;

If she remarried before witnesses said that she is still married, she may remain married. (This shows that we are concerned for disgrace to Beis Din!)

Retraction (Rav Nachman): I was about to rule like I taught. Now that you refuted me, I will abstain.

Rav Nachman reversed the decision of Beis Din, and was not concerned for the disgrace to Beis Din.

An observer thought he erred, but this is not true. Rather, he found that Tana'im argue about whether or not we are concerned for disgrace to Beis Din.

(Mishnah - R. Yehudah): We do not establish a man to be a Kohen based on one witness;

R. Elazar says, this is only if this is challenged; if no one argues, we establish a man to be a Kohen based on one witness;

R. Shimon ben Gamliel says, we establish a man to be a Kohen based on one witness.